counter would change if we change system clock

[yeganehaym]

if I set timer for 30 minutes and I change system clock to 5 minutes earlier, timer would increase by 5 minutes

[yeganehaym]

I def a variable named startTime in the code and save start time instead of current time and it fixed
at least working for me
I wanted to change your code and pull a request but I saw your code is depend on current Time
so I regretted for now to check code more to a safer code